VIDEO VOTE: You can watch Richard Wiseman鈥檚 paper snow videos and vote for the most realistic one.
Perched precariously on a wobbly chair, I balance a bucket full of white paper over the top of a large black vertical screen in front of me. Then I upend the container, releasing a blizzard of twirling paper strips over Richard鈥檚 head. This is no prank: I am helping conduct serious research into the making of artificial snow. The aim is to settle a dispute between the most unlikely of contestants: scientists and circus clowns.
My snowstorm recreates a special effect used in a Russian clown show called Slava鈥檚 Snowshow. The act involves a great deal of fake snow showering down on the performers and the audience. Cheap and reusable, bits of paper turn out to be the ideal snow substitute. Twirling in the air as they descend, the small paper rectangles do a convincing impression of falling snow.
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The effect fascinated Richard Wiseman, a psychologist at the University of Hertfordshire in the UK, when he saw the show in New York in September. Sitting in the dark theatre, surrounded by whirling bits of paper, he couldn鈥檛 help wondering if science could help the clowns put on an even better show. The dimensions of the paper strips must affect how much they twirled and the way they fell, he reasoned. Could their size be fine-tuned to maximise their similarity to a real snowstorm?
Wiseman contacted the clowns, who doubted he could better their standard paper dimensions 鈥� after all, they had settled on them only after much trial and error. 鈥淭hese clowns have been working on this effect for nearly 20 years,鈥� says Gwena毛l Allan, one of their management team. Still, they accepted his offer. 鈥淲e love silly ideas,鈥� says Allan. 鈥淲ill science prevail over clown practice?鈥�
Thus was born Wiseman鈥檚 idea of scientifically assessing the twirliness of different-sized pieces of paper. 鈥淚t鈥檚 clown versus science,鈥� he says.
鈥淭hus was born the idea of assessing the twirliness of pieces of paper. It鈥檚 clown versus science鈥�
So in November I hiked up to Wiseman鈥檚 lab to help him create a snowstorm. His study involves testing numerous batches of paper of varying size. He films the paper falling against a dark background and asks a group of volunteers to rate each batch for its similarity to snow. He鈥檚 not studying how real snow falls, because his measure of whether his creations look like snow is the observer鈥檚 perception. It鈥檚 all about the illusion.
To keep the experiment simple, Wiseman and colleague Sarah Wood investigated how the paper鈥檚 fall would be affected by changing only one variable: the ratio of the length to the width, known as the aspect ratio. The clowns use 40-by-15 millimetre strips of paper. Keeping the length of the strip constant, Wiseman started by increasing the width in 2 mm increments, starting at 11 mm. So far the widest strip he has tried is 23 mm.
As the strips got wider they appeared to twirl more slowly, with the 40-by-23 mm batch revolving slowest of all. By eye, the batches did not seem to differ greatly in their speed of descent. The wider strips did seem to fall more vertically, however, with the thinner strips more prone to fluttering out sideways. 鈥淪mall differences created quite different patterns,鈥� Wiseman says.
He has even intrigued a group of sensible physicists into helping crack the problem of designing the perfect artificial snowflake. Perhaps it helps that his Hertfordshire colleague Arne Hold酶 is a Norwegian who grew up 200 kilometres north of the Arctic Circle. As Hold酶 puts it, in his time he has 鈥渟een a lot of snow鈥�. He has agreed to try to model the forces acting on the falling paper. 鈥淔rom a fluid-mechanics point of view, it鈥檚 an interesting problem,鈥� he says.
Hold酶 is more used to modelling the behaviour of real snow and is realistic about what can be achieved from research on clown snow. 鈥淚 don鈥檛 necessarily see I鈥檓 going to become a millionaire. But getting new information is always useful.鈥�
As is often the way, the dirty work falls to a PhD student: in this case Daniel McCluskey, who is helping Wiseman work out what鈥檚 going on. In theory, making the strips of paper wider should increase their inertia along the longest axis and make them rotate more slowly in that plane. On the face of it, that seems to explain Wiseman鈥檚 results.
In practice, however, the strips of paper have three axes about which they can rotate, and because they are not rigid they can also bend and flop, making it even harder to model their behaviour. 鈥淭hey are tumbling around all over the place,鈥� McCluskey says.
There are other complications. In terms of how quickly the strips fall, making the paper wider could well cause such a small increase in drag that it would make little appreciable difference, says McCluskey. But their rotation would affect drag too. He speculates that the thinner strips fell more sideways because they are subject to more horizontal forces due to their faster rotation along the long axis. He is still not sure what鈥檚 really happening, though. 鈥淚t鈥檚 very chaotic,鈥� he says. However, he insists the problem is not insoluble. 鈥淭here鈥檚 likely to be a predictability to it once you know what鈥檚 going on.鈥�
The physics may yet be murky, but perhaps what really counts is whether the paper does a good impression of snow. Happily, that鈥檚 a lot easier to work out. Wiseman and Wood have shown the films to 51 people so far and asked them to give the different batches marks out of 20 for how much they resembled snow.
The paper that was rated highest was the 40-by-23 mm batch: the widest strips, and the ones with the slowest rotation. It scored 6.1, just beating the clown鈥檚 current 40-by-15 mm strips, which scored 5.6. 鈥淭he science suggests [the wider strips] will obtain better effects,鈥� says Wiseman.
The clowns seem to have taken the news well. They are considering testing Wiseman鈥檚 recommended paper dimensions under the air blowers used in their theatres. 鈥淲e will certainly try experimenting,鈥� says Allan. Science, 1; clowns, 0.
